Catalysis is a change in the rate of a chemical reaction due to the participation of a material called a catalyst. Catalysts that speed the reaction are called positive catalysts. Catalysts that slow the reaction are called negative catalysts, or inhibitors. Unlike reactants, a catalyst is not consumed by the reaction itself.
A catalyst works by providing an alternative reaction pathway to the reaction product. The rate of the reaction is increased when this alternative route has a lower activation energy than the reaction route not mediated by the catalyst. Catalysts can also enable reactions that would otherwise be blocked or slowed by a kinetic barrier. The catalyst may increase reaction rate or selectivity, or enable the reaction to proceed at lower temperatures than would otherwise be possible. As such, catalysts can be very valuable tools in industrial processes.
There can be drawbacks to the use of catalysts. For example, tin compounds are used extensively in Industrial products such as coatings, as catalysts for isocyanate/hydroxyl reactions. Unfortunately, often the catalyst levels required to provide acceptably fast cure rates and final product properties typically result in a short application time window after the components are mixed. Further improvements in reaction rate by adding additional catalyst are precluded because the pot life of the resulting compositions will be even shorter. It would be desirable to catalyze chemical reactions using methods and catalysts that overcome these drawbacks of the prior art by lengthening the pot life of the composition or by accelerating the reaction rate after application without adversely affecting the pot life.